Study On The Absorption Diversity Of Different Cadmium Accumulative Tomato Varieties In Soil

Cadmium?Cd?pollution is one of the most common soil heavy metal pollution.Cd is highly reactive and toxic,which can cause great harm to human body.According to the National Soil Pollution Survey Bulletin in 2014,the rate of soil Cd in China is 7.0%and the pollution is serious.In order to cope with the increasingly serious pollution of soil heavy metals,the selection,cultivation and utilization of different accumulative crop varieties have become a hot topic at home and abroad.At present,the research of Solanum fruit vegetables is still relatively lack.It is very necessary to study the different genotypes of Solanum fruit vegetables in depth and systematically,and to provide a theoretical basis for the determination of different types of vegetables with targeted soil heavy metals Cd.Therefore,in this study,tomato was selected as the research object,high and low accumulation tomato varieties were screened from the common cultivars planted in Hebei.The influence and contribution of different accumulative varieties and their soil microorganism on the bioavailability of soil Cd were analyzed,and the difference characteristics of Cd absorption were explored.Based on that,the soil Cd threshold of different accumulative tomato varieties was determined by empirical study,which provided important scientific theoretical basis for reducing the risk of tomato Cd pollution,ensuring tomato production and controlling soil zoning in Hebei.The main results are as follows:?1?Through hydroponic test,pot experiment and cluster analysis,the differences of resistance and Cd accumulation of ten varieties of tomato cultivars to Cd stress were studied.The low accumulative variety Provence,which has the lowest Cd uptake ability and the strongest resistance to Cd and the high accumulation type Cooperative X,which has the highest Cd uptake ability and moderate resistance to Cd were screened out.Under the condition of Cd 0.3⁰.6 mg/L hydroponics,the accumulation of Cd by Cooperative X was about 12.8 times of Provence.?2?The activation effect of high accumulation and low accumulation tomato varieties on insoluble Cd was studied by hydroponic experiment.The results showed that the promoting effect on the activation of Cooperative X on insoluble Cd was greater than that of Provence.The low accumulation variety Provence significantly promoted the dissolution of the insoluble CdCO₃,which increased the concentration of Cd by 39.78%,but had no obvious dissolving effect on the insoluble CdS.The high accumulation type Cooperative X had a significant effect on the viability of CdS and CdCO₃.The increase of Cd concentration in solution was 51.04%and 62.55%respectively.?3?The effects of two accumulation tomato varieties and their soil microorganism on soil available Cd were studied through pot experiments.The results showed that under the condition of Cd contaminated soil,the individual effect of Provence and Cooperative X increased the content of effective soil Cd by 3.16%and 5.26%respectively,and soil microorganism increased the content of effective soil Cd by 27.37%,and the effect of Provence and Cooperative X with soil microorganism increased the content of effective Cd in soil by 33.68%and 34.74%respectively.The interaction of tomato plants,soil microorganisms and tomato plants soil microorganism can improve the bioavailability of Cd in soil.?4?According to the pot experiment results of tomato varieties and their soil microorganism on the soil effective Cd,the contribution rate of tomato varieties and their soil microorganism to the increase of soil effective Cd was further analyzed.The results showed that in the Cd contaminated soil,the contribution rates of Provence and Cooperative X were 13.02%and 17.62%respectively,and the rates of soil microorganism were 79.41%and 76.52%respectively.The contribution of tomato and soil microorganism were 1.03%¹9.92%,which accounts for a certain positive effect on the increase of available Cd in soil.?5?Through two years of field trials,the total Cd content and effective Cd content of Cooperative X in high accumulation tomato cultivars were studied.The results showed that the linear,logarithmic,two times,exponent and power function relations between the soil Cd content and the Cd content of tomato varieties reached extremely significant level?r?0.78?.Thus,according to the national food pollutant limit standard?Cd<0.05 mg/kg?,the Cooperative X soil of high accumulation tomato varieties was determined.The threshold of soil total and available Cd content were 0.42 mg/kg and 0.07 mg/kg respectively.Compared with the soil Cd threshold of Provence tomato varieties determined by the previous research group,the difference between the two accumulative soil Cd threshold was greater than that of the 0.8 mg/kg.In view of this,it is suggested that Cooperative X should be planted only in soils with Cd content below 0.4 mg/kg.In summary,this study screened the low accumulative tomato varieties Provence and high accumulation type Cooperative X and revealed the contribution and difference characteristics of different accumulated tomato varieties and their soil microbes on soil Cd bioavailability,and thus determined the Cd threshold of two varieties of tomato varieties for the future agricultural soil Cd pollution.The selection of agronomic measures for regional management provides an important theoretical basis.